1. Field of the Invention
The invention relates to a data communication system, particularly to data communication system for effecting data communication between a portable device and a computer, and a connector cable and communication adapter medium used in the data communication system.
This application is a counterpart of Japanese patent application Serial Number 28778/2001, filed Sep. 18, 2001, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
A mobile radiophone has become recently widely used remarkably in Japan, and telecommunications companies employ their own communication systems while a standardized communication system has not been employed. For a digital cellular phone, there are communication systems such as a PDC (Personal Digital Cellular) system, cdmaOne system and the like. For a PHS (Personal Handyphone System), there are communication systems such as a guarantee system, a best effort system and the like. The PDC system used here is a TDMA (Time Division Multiple Access) system which is standardized in Japan. Meanwhile, the cdmaOne system is a radio communication system complying with an international standard and is characterized in a high data transmission speed compared with the PDC system. The guarantee system in the PHS complies with a PIAFS (PHS Internet Access Forum Standard) v2.0 to use a fixed transmission speed while the best effort system in the PHS complies with PIAFS v2.1 to use a valuable transmission speed.
FIG. 5 is a table showing an outline of communication protocols, a hardware specification, and an dedicated connector in the PDC system, the guarantee and best effort systems in the PHS as examples of the communication systems. The dedicated connector is varied in the number of the pin in response to the difference in hardware specification, differentiated in shape, and common or not common in signal line, which are inherent in the respective communication systems.
Accordingly, when a user effects data communication with respect to an external device such as the Internet using a computer such as a mobile computer while using these cellular phones as radio terminals, the user has to purchase an independent or separate data communication adapter to be suited for the cellular phone so as to be connected thereto, so that an inconvenience is given to the user. Meanwhile, manufacturers manufacturing these data communication adapters have to supply data communication adapters to a client which adapters are differentiated corresponding to cellular phones of respective telephone companies.